Water Rushes Down Grand Canyon in High Flow Experiment

Interior Secretary Dirk Kempthorne Wednesday pulled a lever at Glen Canyon Dam to release the water for a 60-hour "high flow test." The flood of water is expected to push sand built up at the bottom of the river's channel into a series of sandbars and camping beaches along the river, replenishing the sediment that has been held back behind the dam.

"The water will be released at a rate that would fill the Empire State Building within 20 minutes," Kempthorne said. "It will transport enough sediment to cover a football field 100 feet deep with silt and sand."

Water is released from Glen Canyon Dam. (Photo courtesy DOI)

The experiment is an inter-agency research effort conducted by three Department of the Interior bureaus – the U.S. Geological Survey, USGS; the Bureau of Reclamation, which operates Glen Canyon Dam on the Colorado River; and the National Park Service, which manages Grand Canyon National Park.

High flows also create areas of low-velocity flow, or backwaters, used by young native fishes, particularly endangered humpback chub, one of four remaining native fish in the Grand Canyon.

USGS scientists will be monitoring how the high-flow releases affect the survival of a population of young humpback chub.

Researchers will collect data on the changes in sandbars before, during, and after the high flow. This data will be used to improve the predictive capabilities of the existing sediment model and determine the optimal peak flows of future high-flow experiments.

But a conflict over future high-flow experiments has caused a rift within the Department of the Interior.

The fight pits the U.S. Bureau of Reclamation, which is pushing a plan supported by water and power interests, against the National Park Service which says the plan will harm wildlife and habitat in Grand Canyon National Park, according to a national organization of government employees in natural resource agencies.

Public Employees for Environmental Responsibility, PEER, released documents last week that illuminate the intra-agency conflict.

The Bureau of Reclamation released its plan's Environmental Assessment, EA, in early February, allowing only 15 days of public comment, and concluded that its experiment would have "no significant environmental impact," eliminating the need for further review.

The Grand Canyon of the Colorado River (Photo courtesy USGS)

The National Park Service, which was excluded from the plan's development, is objecting because the plan does not permit any further high flows during the five-year experimental period so that power generation can be maximized.

Instead, the plan calls for a two-month regime of steady flows during September and October over a five-year period.

In a February 19, 2008 comment letter to the Bureau of Reclamation's Regional Environmental Manager Randall Peterson, Grand Canyon National Park Superintendent Steve Martin pointed to the lack of scientific basis for the "steady flow periods" and for conducting only one high-flow event in a five-year span.

"It is not apparent where the 80 million dollars in research, conducted over the last 10 years has been used in this decision-making process," wrote Martin. "Our analysis shows that this document is not consistent with current best information."

Martin wrote, "Based on current scientific information, lack of inclusion of additional high flows could lead to impairment of the resources of Grand Canyon National Park."

Martin says high flows should be staged every year or two, whenever enough sediment builds up behind the dam.

Further, the Grand Canyon Trust, a nonprofit group based in Flagstaff, Arizona is suing the Interior Department to get it to honor commitments made in 1996 to seasonally adjust flows and stage more high-flow events.

"The water released during the test will not change the amount of water to be released over the course of the 2008 water year," said Larry Walkoviak, Regional Director of Reclamation's Upper Colorado Region.

"The current plan of operations calls for releasing 8.23 million acre-feet of water from Glen Canyon Dam. That water flows downriver to Lake Mead for use by the Lower Colorado River Basin States and Mexico," he said. "The experimental flows are included within this annual volume. Monthly releases later in the year will be adjusted downward to account for the water released during the experiment."

The high-flow test period ends Friday when the gush of water will be shut off and the Colorado River will return to its usual clear, slow flow.

Copyright Environment News Service (ENS) 2008. All rights reserved.